(a) Field of the Invention
The present invention relates to a photoconductive sensitive material for use in electrophotography.
(B) Description of the Prior Art
In Japanese Patent Publication No. 16198/1968 there is disclosed a photoconductive sensitive material comprising a layer of selenium (Se) deposited through evaporation on a conductive support and a layer of polyvinyl carbazole on said layer of Se. This photosensitive material is so designed as to give rise to electrons and holes in the Se layer by exposing it to light and to transfer the thus generated holes onto the surface of the photosensitive material by virtue of said layer of polyvinyl carbazole. In other words, Se works as a charge generating substance and polyvinyl carbazole works as a charge transferring substance.
In Japanese Patent Open No. 11536/1972 and Japanese Patent Open No. 11537/1972 there is disclosed a photosensitive material for use in electrophotography wherein a charge generating substance is mixed with a charge transferring substance to constitute one and the same layer.
Those photosensitive materials employing a charge generating substance in combination with a charge transferring substance promise an enhanced sensitivity compared with a photosensitive material employing a photosensitive layer wherein ZnO resin is dispersed therein or one employing a photosensitive layer of polyvinyl carbazole. Besides, various ways have been tried to improve the photosensitive materials of the type comprising the combination of a charge generating substance and a charge transferring substance. However, the proposals made to date are no more than those disclosed in Japanese Patent Open No. 18543/1972, Japanese Patent Open No. 18544/1972, Japanese Patent Open No. 30331/1972, Japanese Patent No. 30332/1972, etc. which mostly deal with the improvement of the charge generating substances. An attempt to improve the charge transferring substance is unprecedented.
As the charge transferring substances hitherto known, there are, for instance, polyvinyl carbazole, polyvinyl anthracene, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitrofluorenone, dinitroanthracene, dinitroacridene, dinitroanthraquinone, 2-phenyl anthracene, 2-phenyl indole, etc.
However, as a matter of fact, the conventional photosensitive materials prepared by employing these known charge transferring substances are still insufficient in sensitivity.